HGTDTruthTrackDecorationAlg.h

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/*
  Copyright (C) 2002-2025 CERN for the benefit of the ATLAS collaboration.
*/
 
#ifndef HGTDTRACKEXTENSIONALG_TRUTHDECORATION_H
#define HGTDTRACKEXTENSIONALG_TRUTHDECORATION_H
 
// Base Class
#include "AthenaBaseComps/AthReentrantAlgorithm.h"
 
#include "xAODTracking/TrackParticleContainer.h"
#include "StoreGate/WriteDecorHandleKey.h"
#include "StoreGate/ReadDecorHandleKey.h"
#include "StoreGate/ReadHandleKey.h"
#include "ActsEvent/TrackContainer.h"
#include "ActsEvent/MeasurementToTruthParticleAssociation.h"
#include "Identifier/Identifier.h"
#include "HGTD_Identifier/HGTD_ID.h"
 
#include "src/detail/AtlasMeasurementSelector.h"
#include "src/detail/OnTrackCalibrator.h"
#include "src/detail/TrackFindingMeasurements.h"
#include "src/detail/MeasurementIndex.h"
#include "src/detail/Definitions.h"
 
#include "ActsCalibrators/xAODUncalibMeasSurfAcc.h"
#include "ActsGeometryInterfaces/ITrackingGeometrySvc.h"
 
 
#include "xAODTruth/TruthParticleContainer.h"
 
#include <array>
#include <cstddef>
#include <unordered_map>
 
namespace ActsTrk {
  
  using AtlUncalibSourceLinkAccessor = detail::UncalibSourceLinkAccessor;
 
  enum class ClusterTruthOrigin {
    UNIDENTIFIED = 0,       // ITk track is not associated with a truth particle, so not identified
    TRUTH_PARTICLE = 1,     // originates from the tested truth particle
    UNRELATED_PARTICLE = 2, // originates from a particle that is unrelated to the ITk track
    SECONDARY = 3           // originates from some secondary interaction
  };
 
  class HGTDTruthTrackDecorationAlg
    : public AthReentrantAlgorithm {
 
  public:
    using AthReentrantAlgorithm::AthReentrantAlgorithm;
    virtual ~HGTDTruthTrackDecorationAlg() = default;
    
    virtual StatusCode initialize() override;
    virtual StatusCode execute(const EventContext&) const override;
    
  private:
 
    //HGTD Clusters and Cluster to Truth
    SG::ReadHandleKey<xAOD::TrackParticleContainer> m_trackParticleContainerName {this, "TrackParticleContainerName", "", "Name of the TrackParticle container"};
    SG::ReadHandleKey<ActsTrk::TrackContainer> m_trackContainerKey{this, "ACTSTracksLocation", "HgtdTracks", "Output track collection (ActsTrk variant)"};
    SG::ReadHandleKey<xAOD::UncalibratedMeasurementContainer> m_uncalibratedMeasurementContainerKey_HGTD{this, "UncalibratedMeasurementContainerKey_HGTD", "HGTD_Clusters", "input cluster collections for HGTD"};
    SG::ReadHandleKey<MeasurementToTruthParticleAssociation>  m_hgtdClustersToTruth { this, "HgtdClustersToTruthAssociationMap", "HgtdClustersToTruthParticles", "Association map from HGTD measurements to generator particles." };
 
    SG::ReadDecorHandleKey<xAOD::TrackParticleContainer> m_hgtdTrackLinkKey {this, "hgtdTrackLink", m_trackParticleContainerName, "hgtdTrackLink", "Link to Hgtd track"};
    SG::ReadDecorHandleKey<xAOD::TrackParticleContainer> m_truthParticleLinkKey {this, "truthParticleLink", m_trackParticleContainerName, "truthParticleLink", "Link to Truth particle"};
    
    // Truth decorations
    SG::WriteDecorHandleKey<xAOD::TrackParticleContainer> m_layerClusterTruthClassKey { this, "HGTD_cluster_truth_class", m_trackParticleContainerName, "HGTD_cluster_truth_class", "Decoration for cluster truth classification" };
    SG::WriteDecorHandleKey<xAOD::TrackParticleContainer> m_layerClusterShadowedKey { this, "HGTD_cluster_shadowed", m_trackParticleContainerName, "HGTD_cluster_shadowed", "Decoration for shadowed cluster" };
    SG::WriteDecorHandleKey<xAOD::TrackParticleContainer> m_layerClusterMergedKey { this, "HGTD_cluster_merged", m_trackParticleContainerName, "HGTD_cluster_merged", "Decoration for merged cluster" };
    SG::WriteDecorHandleKey<xAOD::TrackParticleContainer> m_layerPrimaryExpectedKey { this, "HGTD_primary_expected", m_trackParticleContainerName, "HGTD_primary_expected", "Decoration for primary expected cluster" };  
      
    ActsTrk::detail::xAODUncalibMeasSurfAcc m_surfAcc{};
    ServiceHandle<ActsTrk::ITrackingGeometrySvc> m_trackingGeometrySvc{this, "TrackingGeometrySvc", "ActsTrackingGeometrySvc"};
 
    std::unique_ptr<SG::AuxElement::Accessor<int>> m_acc_nHgtdHits;
 
    const HGTD_ID* m_id_helper{nullptr}; 

    struct TruthTrackExtensionData {
      std::vector<int> truthClassVec = {-1, -1, -1, -1};                 
      std::vector<char> isShadowedVec = {false, false, false, false};    
      std::vector<char> isMergedVec = {false, false, false, false};      
      std::vector<char> primaryExistsVec = {false, false, false, false}; 
    };
    
    struct ClusterTruthInfo {
      ClusterTruthOrigin origin = ClusterTruthOrigin::UNIDENTIFIED;
      bool is_shadowed = false;
      bool is_merged = false;
    };

    TruthTrackExtensionData createTruthDecoration(
      const xAOD::TruthParticle* truthParticle,
      const typename ActsTrk::TrackContainer::ConstTrackProxy trackProxy,
      const ActsTrk::MeasurementToTruthParticleAssociation* association_map) const; 
    
    static constexpr std::size_t s_nHgtdLayers = 4;
    using HgtdLayerFlags = std::array<char, s_nHgtdLayers>;
    using PrimaryExpectedLookup = std::unordered_map<std::size_t, HgtdLayerFlags>;

    StatusCode buildPrimaryExpectedLookup(
      const xAOD::UncalibratedMeasurementContainer & measurementContainer,
      const ActsTrk::MeasurementToTruthParticleAssociation* association_map,
      PrimaryExpectedLookup& lookup) const;
 
  };
  
} // namespace ActsTrk
 
#endif